1. Field of the Invention
The present invention relates to a vehicle wheel on which a pneumatic tire can be mounted; the wheel has a rim which is provided laterally outwardly with rim flanges, adjacent to which, on the radially outer side of the rim, there are seating surfaces for the tire, which is a pneumatic tire comprised essentially of rubber or rubber-like synthetic materials and having a carcass with textile and/or metallic load-carrying cords; the carcass is anchored in the beads via inextensible core rings.
2. Description of Prior Art
A vehicle wheel of this general type is widely used at the present time. In order to improve this wheel system, numerous structural and material variations have been proposed in order to take into consideration the technical requirements of the market place. These requirements can be divided into several groups, namely "concept" (small weight of the system, large installation space for brakes accompanied by little space requirement of the wheel), "design characteristics during normal operation", i.e. at operational air pressure (driving comfort, driving stability, driving safety, durability, economy), "design characteristics in the pressureless state" (sufficient emergency operating capability without damage to the tire).
The improvements proposed to date frequently concern either the driving comfort while retaining the remaining driving characteristics, but not providing an emergency operating capability, or an ability to drive in the pressureless state, but with critical drawbacks during normal operation such as with regard to weight and resistance to rolling.
An object of the present invention, while at the same time achieving a reliable emergency operation capability, is to achieve a considerable minimization of the disturbance variables which the tire beads exert via the side wall on the tread.
Summary of the Invention
The vehicle wheel of the present invention may be characterized in that axially inwardly from the seating surfaces, the rim is provided with a support member which has a diameter which is greater than the diameter formed by the rim flanges; the tire wall extends laterally outwardly in a substantially flat manner from the core ring in the region of the rim flange, and in particular extends in an angular range of from 0.degree. to 20.degree. relative to the axis of rotation of the tire; the carcass neutral line passes through this region while avoiding a turning point, and the core ring is eccentrically disposed in a pivotable bead in such a way that when the tire is mounted, the inner diameter of the tire in the bead region is less than it is while the tire is being mounted.
The vehicle wheel of the present invention may also be characterized in that axially inwardly from the seating surfaces, the rim is provided with a recessed mounting portion for each tire bead, and furthermore with at least one support member which has a diameter which is greater than the diameter formed by the rim flanges; in the region of the rim flange, the tire wall extends laterally outwardly in a substantially flat manner from the core ring, and in particular in an angular range of from 0.degree. to 20.degree. relative to the axis of rotation of the tire; the carcass neutral line passes through this region while avoiding a turning point.
Pursuant to further specific features of the present invention, the greatest diameter of the rim flanges may be the same or greater than the center-to-center diameter of the core rings. The carcass neutral line may conform to the function of a catenary curve in that region which is disposed directly laterally outwardly adjacent to the core ring. When the tire is inflated but not under load, the tire wall may rise laterally outwardly in the region of the rim flange at an angle in a range of 0.degree. to 5.degree. relative to the axis of rotation of the wheel. In the region of the rim flange, the carcass may extend nearly horizontally, may be anchored in the bead by being looped around the core ring, and the looped-around carcass end may be disposed on the radially inner side. The diameter of the support member may be greater than the diameter formed by the rim flanges and the wall thickness of the tire wall.
Pursuant to the present invention, the tire side wall is pivotably suspended as a membrane on the rim flange, thus eliminating the need for a rigid and immobile bead zone which in itself has a great weight. This considerably reduces the supporting portion of the carcass, resulting in the advantage of a considerable increase in the traveling comfort at a given tire pressure.
Due to the reduction of the support portion of the carcass, thus stress results in the bead zone. This is very advantageous, especially for truck tires. While the fixed portion of the tire remains completely undisturbed, the forces which arise are absorbed by an increase of the angular region where the tire side wall leaves the rim.
Furthermore, the pivotable, and hence very flexible, connection of the tire side walls brings about a favorable ground support surface which is essentially free of a reactive effect due to a rigidity of the tire side walls. This results in a homogeneous distribution of pressure in the supporting surface. This then results in a uniform distribution of the frictional connection values in the entire region of the supporting surface, and hence in an increase of the frictional connection. In addition, the homogeneous distribution of pressure results in less wear and a more uniform wear pattern.
Finally, the inventive vehicle wheel results in less resistance to rolling, since in the bead region with the relatively small amount of material, such a great deformability, and hence such a great formation of heat, no longer occurs.
During an emergency operation, i.e. when driving in a pressureless condition, the tire rests upon the support member and bulges or curves laterally in such a manner that, in contrast to heretofore known vehicle wheels, contact with the roadway can be reliably avoided. In addition, contact zones having high friction are avoided in the inner side wall regions; with conventional vehicle wheels, such contact zones lead to rapid destruction of the tire. In addition to the rim construction, the design of the tire assures an outstanding emergency operation. As a result of the small support portion of the carcass, due to the flexible side walls up to the rim flange, the reactive operation in this region of the tire is nearly eliminated, hence avoiding destruction of the tire. Initial tests were made with the tire covering stretches of up to 100 km at a speed of about 80 km/h, without any damage resulting to the tire. Since furthermore no critical impairment of the driving conditions were encountered during emergency operation, the best conditions for eliminating the previously customary spare tire were provided.
Due to the eccentric arrangement of the core ring in the tire bead, and the pivotability of the tire bead during mounting, the previously customary well base can be completely dispensed with, thus resulting in the advantage of a larger installation space for the brakes.
The tire can be mounted on a one-piece rim; to surmount the support member, the rim is first moved into the tire approximately at right angles thereto, and the rim is then turned within the tire.
In contrast to wheel systems according to which the tire is mounted radially inwardly on the rim, there is achieved with the present invention the advantage of a simple tire manufacture on conventional machines and in existing types of molds.